QUESTION: A person with a fever (38oC) is given an alcohol rub. As the alcohol evaporates, the algebraic sign for q for the alcohol is ________ and q.

Slides:

Advertisements

Similar presentations

Advertisements

3.3 Phase Changes What are six common phase changes?

Celsius-to-Fahrenheit: F = 1.8C + 32

At what temperature are the Celsius and Fahrenheit readings equal?

Pearson Prentice Hall Physical Science: Concepts in Action

QUESTION: A 25.0 gram sample of a compound is found to be 24% chlorine by mass. What is the percentage of chlorine in a 50.0 g sample of the compound?

Bohr assumed electrons move around the nucleus in circular orbits.

Specific heat is short for “specific heat capacity”

For which pair of molecules is London Dispersion strongest?

QUESTION: How many ways can the magnetism generated by the orbital motion of an electron in a 3p orbital be oriented? A. 1, B. 3, C. 5, D. 7 Magnetism.

Code letters for orbital quantum numbers (l):

QUESTION: Which of the following elements is a transition metal? A. silicon, B. lead, C. sodium, D. chromium SCRIPT: Which of the following elements.

SO3: one Sulfur atom: 16 protons

Uncertainty of g: tenths place

Choice B: Br2(l)  Br2(g)  2 Br(g)  2 Br+(g) + 2e-

A. 2.40x103 km min-1, B. 6.67x10-1 km min-1 C km min-1

Which of these is the formula of a reactant in this reaction?

T = q / C = (-5.00x103 J) / (2.50x103 J K-1) = -2.00K, or –2.00oC.

Specific heat is short for “specific heat capacity”

Ions are formed by loss or gain of electrons.

QUESTION: Which of the following describes an anion? A. a sodium ion (Na+), B. a calcium ion that has lost 2 electrons C. an ion with 8 protons and 10.

QUESTION: Which of the following is a metalloid? A. Potassium, B. Silicon, C. Iron, D. Helium SCRIPT: Which of the following is a metalloid? A.

Mass of proton or neutron: 1.0 u Mass of electron: u

Heat flow: hot-to-cold  stove-to-pot PAUSE CLICK

Ions are formed by loss or gain of electrons.

Warm-Up Think critically: What do you think is happening to the movement of atoms when evaporation occurs? Think critically: What do you think.

A. 0.8 g/mL, B g/mL, C g/mL, D. 1.3 g/mL

To construct the ground state electron configuration,

Diatomic = “di” + “atomic” “di” = Greek prefix; means “two”

One Ca2+ ion: +2 One CO32- ion: -2

There are 3 orbitals in a p subshell (ml = -1, 0, or +1).

Heat refers to energy transferred due to a difference in temperature.

A. unsaturated, B. still saturated, C. supersaturated

Ions are formed by loss or gain of electrons.

Which of the following has the largest size? A. Cl B. Cl-, C. F, D. F-

QUESTION: How many atoms in the acetic acid molecule (CH3COOH) are capable of hydrogen bonding interaction with water molecules? A. 1, B. 2, C. 3, D.

A. solid, B. liquid, C. gas, D. none of these

A. 1.29x10-3 mg/mL, B mg/mL, C. 1.29x10-6 mg/mL

Mathematically, this implies that the ratio of the amount of element

How many neutrons does an O-18 atom have? A. 8, B. 10, C. 16, D. 18

PAUSE CLICK Let’s examine choice A.

QUESTION: How should the result of the following calculation be reported, assuming that 1.8 and 32 are exact numbers? 32 + (1.8)(2.37) A. 36,

Steric number of C in the structure is 3.

What is the Kelvin temperature equivalent to 50.00oF?

HIGHLIGHT carbon in legend

The oxygen-to-carbon ratio in that sample is x over 36.0 HIGHLIGHT

What is the Kelvin temperature equivalent to 25.00oC?

Uncertainty is at least +1/10 of smallest interval.

A. London dispersion forces, B. dipole-dipole interaction,

Change in volume is essentially due to formation of gas

PV work w = - Pex dV = - PexV

A. air, B. gasoline, C. copper wire

Allowed values of principal quantum number (n): positive integers

Which figure below best represents an aqueous solution of CaCl2?

Therefore, the correct answer is A.

The area of a circle is found to be 2.4 cm2. What is the area in m2?

QUESTION: A sample of matter is heated and found to start melting at 75.0oC. While melting, the sample temperature continues to rise to about 85.0oC.

Using modern sign convention, PV work…

Ions are formed by loss or gain of electrons.

For which pair of molecules does dipole-dipole interaction occur?

235UF6 effuses faster than 238UF6

give us something that is light blue, not yellow.

CLICK PAUSE END RECORDING

QUESTION: What is the maximum number of of electrons that can be assigned to a 2p orbital of an atom? A. 2, B. 3, C. 6, D. 10 Pauli’s Exclusion.

A. an element and two compounds, B. two elements and a compound,

We now have a mixture of 3 substances --- the original compound

QUESTION: Consider the pictorial representation shown below for a change in physical state at the molecular level. The picture best represents which of.

represented by a pair of filled circles,

Mole is a group count (just like dozen).

Presentation transcript:

QUESTION: A person with a fever (38oC) is given an alcohol rub. As the alcohol evaporates, the algebraic sign for q for the alcohol is ________ and q for the person is ________. A. positive, positive, B. positive, negative C. negative, positive, D. negative, negative Vaporization is an endothermic process. This means that heat flows into the a liquid as it is transformed into a gas. By convention, q is assigned a positive value for an endothermic process; and q is assigned a negative value for an exothermic process. Consider the following…. A person with a fever (38oC) is given an alcohol rub. As the alcohol evaporates, the algebraic sign for q for the alcohol is ________ and q for the person is ________. Fill in the blanks with the words positive or negative. PAUSE CLICK Vaporization is an endothermic process. This means that heat flows into the a liquid as it is transformed into a gas. In the transformation molecules spread out…. In order for molecules to move farther apart, they need energy to be able to overcome the forces that are holding them together in a liquid. The alcohol molecules that go into the gas phase gain this energy through random collisions with neighboring molecules, including the molecules in the person’s body. CLICK As a matter of convention, the amount of heat flow,…q HIGHLIGHT q is assigned a positive value for an endothermic process. HIGHLIGHT positive and endothermic Therefore, the algebraic sign for the alcohol is positive. FILL IN THE BLANK WITH “positive” The heat that flowed into the alcohol came from the person’s body. So, we say that there is heat flow OUT of the person. The outflow of heat is what we would call an exothermic process. HIGHLIGHT exothermic and, by convention, the value of q is assigned a negative value for an exothermic process. HIGHLIGHT negative Since alcohol evaporates rapidly, this explains how an alcohol rub can be useful in quickly reducing the temperature of someone with a fever. CLICK PAUSE END RECORDING

Video ID: 8-5-1 © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Assisted by Johuan Gasery In partial fulfillment of the requirements for CHEM 481, Fall 2008.